SYDNEY, AUSTRALIA—The city of Mahendraparvata has been mapped on Phnom Kulen Mountain, located to the north of the Angkor Wat Complex in Cambodia, by archaeologists using airborne laser technology carried by a helicopter. Some 36 buildings had previously been recorded on the jungle-covered mountain, but it wasn’t known how they fit together. More than two dozen temples, and traces of canals, dykes, and roads laid out in regular city blocks have now been mapped. “We see from the imagery that the landscape was completely devoid of vegetation. One theory we are looking at is that the severe environmental impact of deforestation and the dependence on water management led to the demise of the civilization,” said Damian Evans of the University of Sydney.